The major objectives of this research proposal are to determine the antigenic and covalent structures of several different serotypes of group A streptococcal M protein in an attempt to define those regions of the M protein molecule which are responsible for type-specific protective immunity as opposed to those regions which may contain extraneous antigens some of which may be cross-reactive with host tissues. Based on the detailed information of the chemical and antigenic structure of several M proteins we plan to construct polyvalent immunogens from synthetic peptides which can be safely and efficaciously administered as vaccines to humans. M proteins will be extracted from whole streptococcal cells by limited proteolysis with pepsin. The purified polypeptides (pep M) will be analyzed chemically for amino acid content and amino terminal amino acid sequences. The polypeptides will be cleaved as appropriate with cyanogen bromide or proteolytic enzymes and the peptide fragments will be purified and characterized by automated Edman degradation. The immunoreactivity of the various peptide fragments will be assessed in tests of the inhibition of streptococcal opsonization as well as in the inhibition of enzyme-linked immunosorbent assays (ELISA). Active fragments will be convalently conjugated to carrier polylysine to serve as immunogens in rabbits, mice, and guinea pigs. Those peptide fragments capable of raising type specific or cross-reactive protective antibodies will be synthesized in an automated peptide synthesizer. The synthetic peptide fragments will then form the basis of a fully defined polyvalent M protein vaccine. During the above studies we plan to proceed cautiously with small pilot studies of the immunogenicity of already available highly purified pep M protein preparations. The immunogenicity of several pep M proteins (pep 6 and pep M5) will first be studied separately and then as a multivalent vaccine. Eventually, we plan also to cautiously test the synthetic peptide vaccines in man.